Lethal Performance pushes its Shelby Project past 1,100 rwhp with a built 5.8 and a 4.0-liter blower

We already established that for most normal people, a 662hp '13 Shelby GT500 is more than enough. For denizens of the 5.0&SF nation, it's really just a starting point. And, for the crew at Lethal Performance, such a car is a head-start to the end result of huge performance gains on the dyno and at the track.

That certainly proved to be the case as Team Lethal immediately tore into its Performance White '13 Shelby GT500 in the name of high-performance science. When we last left this ride it was running deep into the 9-second zone and putting down over 830 rwhp with bolt-ons and nitrous. In short, it was already a really serious street machine.

Of course, that was just the beginning. We all knew that as a top distributor for Whipple superchargers, Lethal would be quick to swap out the factory supercharger for one of these twin-screw units. It's a pretty standard move for GT500 owners to make a move for the 2.9-liter supercharger. However, we know how the Team Lethal bunch is. They didn't pass Go, or collect a 2.9-liter. They headed straight for the big 4.0-liter.

"We initially wanted to test both the 4.0-liter and the 2.9-liter to see how they compared to the stock TVS as well as each other. However, we just didn't have the time to do it all so we went with what we knew would make big power," Lethal's Jared Rosen explained. "Having already made over 1,000 rwhp with our '10 GT500, we figured the results with the '13 would be even better. I'm hearing that there will be a 4.5-liter in the cards soon."

At least that was the best laid plan. However, when you are pushing the envelope with a stock engine, sometimes there are casualties. Such was the case with the stock Trinity. A crank damper failed and took the balance out of whack and the engine with it. That put our blower upgrade story on pause and turned this examination into a built engine with the big blower. Even better.

"I was definitely surprised when Jake notified me about the balancer breaking. However, it wasn't until we actually pullied down the 4.0-liter that we figured out the crank was damaged. It just wasn't picking up more power when we increased boost," Jared added. "I suppose when the balancer broke it also hurt the crank, and we were missing 5 degrees of timing the entire time. At that point, it wasn't even a question whether we would build the motor or not. If we're gonna do it, we're gonna do it right and then some."

To that end, Lethal had a rugged 5.8 constructed to take as much as the 4.0-liter can dish out. Lethal then backed it up with a monster fuel system made to flow enough E85 to support the heavily boosted 5.8. The results are the stuff of legend.

"Just like our previous builds, we really don't have anything set in stone. We take it how it comes and make changes as necessary. The one thing we do know is that we want to go fast. So whatever it takes to accomplish that, we'll do," Jared said. "The only thing we really don't want to do is put a cage in it. We've already got one GT500 with a cage in it, so I'm not looking for another."

For now, read on to see how the most powerful factory Mustang ever created became twice as powerful.

Horse Sense: The big, 4.0-liter supercharger was an option on the '10-'12 Cobra Jet drag car offered for sale by way of Ford Racing Performance Parts dealers. However, FRPP's primary twin-screw offering is the stock-hood-friendly, 2.9-liter version available for both Coyote (PN M-6066-MGT624D) and GT500 (PN M-6066-MSVT29TD) applications.

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We knew that the combination of a Whipple 4.0-liter with a fortified Trinity engine would generate big power, but we didn't quite expect the number to keep rolling this high into the four-digit range. Suffice it to say this is a happy marriage. Seriously, we were impressed when the Trinity 5.8 picked up 153.42 hp and 144.22 lb-ft of torque with the typical pulley, tune, and exhaust bolt-ons. Color us astounded that the built motor with 24.80 psi of Whipple boost—courtesy of an ATI 15-percent overdrive balancer and 3.50-inch blower pulley—tacked on an additional 440.98 hp and 331.09 lb-ft of torque. Some cars would be considered fast with those numbers as their total power and torque numbers.

"This is the most powerful car we've owned so far and it seems like it really didn't take that much to get there. I think the biggest factor with this car as opposed to our '10 GT500 is compression. When we built the '10 with both E85 and high-compression these engines weren't that popular. Shortly after that car was finished is when people started building motors with higher compression," Jared explained. "So for our 2013 we did just that and built a high-compression motor knowing that it would make more power with less boost."